12/1/2009. Chapter 19: Hemorrhage. Hemorrhage and Shock Occurs when there is a disruption or leak in the vascular system Internal hemorrhage

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1 Chapter 19: Hemorrhage Hemorrhage and Shock Occurs when there is a disruption or leak in the vascular system External hemorrhage Internal hemorrhage Associated with higher morbidity and mortality than external hemorrhage Physiological Response to Hemorrhage Defining Shock The body s initial response to hemorrhage is to stop bleeding by chemical means (hemostasis) This vascular reaction involves: Local vasoconstriction Formation of a platelet plug Coagulation Growth of fibrous tissue into the blood clot that permanently closes and seals the injured vessel If hemorrhage is severe, these mechanisms may fail, resulting in shock (hypoperfusion) Shock is best defined as inadequate tissue perfusion Can result from a variety of disease states and injuries Can affect the entire organism or can occur at a tissue or cellular level Shock is not adequately defined by: Pulse rate Blood pressure Cardiac function Hypovolemia Loss of systemic vascular resistance 1

2 Tissue Oxygenation Cardiac Output Adequate oxygenation of tissue cells (perfusion) depends on three components of the cardiovascular system Heart Vasculature Lungs When any one of these malfunctions, a decrease in cellular oxygenation may occur The amount of blood separately pumped by each ventricle per minute, usually expressed in liters per minute Determined by multiplying the heart rate by the volume of blood ejected by each ventricle during each beat (stroke volume) A crucial determinant of organ perfusion Depends on: Strength of contraction Rate of contraction Amount of venous return available to the ventricle (preload) Shock Baroreceptor Reflexes Fick principle The vasculature Pressure gradients Peripheral vascular resistance (afterload) Viscosity Microcirculation Vasomotion Help maintain blood pressure by two negative feedback mechanisms By lowering blood pressure in response to increased arterial pressure By increasing blood pressure in response to decreased arterial pressure 2

3 Chemoreceptor Reflexes Compensatory Mechanisms Low arterial pressure may stimulate peripheral chemoreceptor cells that lie within the carotid and aortic bodies When oxygen or ph decreases, these cells stimulate the vasomotor center of the medulla CNS ischemic response Hormonal mechanisms Adrenal-medullary mechanism Renin-angiotensin-aldosterone aldosterone mechanism Vasopressin mechanism Atrial natriuretic factor Reabsorption of tissue fluids Splenic discharge of blood The Lungs The Body as a Container Adequate cellular oxygenation requires that adequate oxygen be available to red blood cells at the capillary membrane in the lungs First component of the Fick principle Made possible by: The high arterial pressure of oxygen in inspired air Adequate depth and rate of ventilation Matching of pulmonary ventilation and perfusion The healthy body may be viewed as a smooth-flowing delivery system inside a container Container must be filled to achieve adequate preload and tissue oxygenation 3

4 The Body As a Container The external size of the container of any particular human body is relatively constant The volume of the container is directly related to the diameter of the resistance vessels Any change in vessel diameter changes the volume of the fluid the container holds, thereby affecting preload Blood and its Components Blood Volume Plasma The average adult male has a blood volume of 7% of total body weight The average adult female has a blood volume of 6.5% of total body weight Volume increases significantly during pregnancy Normal adult blood volume is 4.5 to 5 L Remains fairly constant in the healthy body Approximately 92% water The liquid portion of blood Circulates salts, minerals, sugars, fats, and proteins throughout the body Contains three major proteins Albumin Globulins (alpha, beta, and gamma) Fibrinogen 4

5 Red Blood Cells (Erythrocytes) White Blood Cells (Leukocytes). Transport 99% of blood oxygen Remaining 1% is carried in plasma Make up approximately 45% of the blood Most abundant cells in the body Provide oxygen to tissues and remove carbon dioxide Defend the body against various pathogens (bacteria, viruses, fungi, and parasites) Produced in bone marrow and lymph glands A reserve of white blood cells is constantly produced and maintained, but not many are present in a healthy blood stream Reserves are released when pathogens invade the body Platelets. Capillary-Cellular. Relationship in Shock Part of the body's defense mechanism Help stop escaping blood Formed in red bone marrow Work by swelling and adhering together to form sticky plugs (initiating the clotting phenomenon) Stage 1: Vasoconstriction Stage 2: Capillary and venule opening Stage 3: Disseminated intravascular coagulation Stage 4: Multiple l organ failure 5

6 Classifications of Shock. Compensated Shock. Hypovolemic shock Distributive shock Neurogenic shock Anaphylactic shock Septic shock Cardiogenic shock Obstructive shock Characterized by signs and symptoms of early shock Arterial blood pressure is normal or high Treatment at this stage will typically result in recovery Uncompensated Shock. Irreversible Shock. Characterized by signs and symptoms of late shock Arterial blood pressure is abnormally low Treatment at this stage will sometimes result in recovery Characterized by signs and symptoms of late shock Arterial blood pressure is abnormally low Even aggressive treatment at this stage does not result in recovery 6

7 Management and Treatment Plan for the Shock Patient. Initial Assessment. Ensure a patent airway Provide adequate oxygenation and ventilation Restore perfusion Airway Breathing Circulation Disability Expose body surfaces Differential Shock. Assessment Findings Differential Shock. Assessment Findings Shock is assumed to be hypovolemic until proven otherwise Cardiogenic shock Differentiated from hypovolemic shock by one or more of the following: Chief complaint (chest pain, dyspnea, tachycardia) Heart rate (bradycardia or excessive tachycardia) Signs of congestive heart failure (jugular vein distention, rales) Dysrhythmias Distributive shock Differentiated from hypovolemic shock by presence of one or more of following: Mechanism that suggests vasodilation, e.g., spinal cord injury, drug overdose, sepsis, anaphylaxis Warm, flushed skin (especially in dependent areas) Lack of tachycardia response (not reliable) 7

8 Differential Shock. Assessment Findings Detailed Physical Examination. Obstructive shock Differentiated from hypovolemic shock by presence of signs and symptoms suggestive of: Cardiac tamponade Tension pneumothorax Pulmonary embolism Vital signs Pulse Blood pressure Orthostatic vital signs Evaluate patient s ECG Resuscitation. Red Blood Cell Oxygenation. Resuscitation is aimed at restoring adequate peripheral tissue oxygenation as quickly as possible This is accomplished by: Ensuring adequate oxygenation Maintaining an effective ratio of volume to container size Rapidly transporting the victim to an appropriate medical facility First requirement for adequate tissue oxygenation For adequate red blood cell oxygenation: The patient must have a patent airway Ventilation must be supported with high FiO2 If necessary, ventilations should be assisted with positive pressure Correct any airway abnormalities that interfere with adequate ventilation 8

9 Ratio of Volume. to Container Size Adequate oxygen-carrying capacity requires that the container be full of fluid May be accomplished by: Decreasing the size of the container Especially in shock states not associated with hemorrhage Possible use of vasoactive medications in some cases of distributive shock Volume replacement may be necessary Fluid Resuscitation in Shock. Crystalloids. Hypertonic. and Hypotonic Solutions Solutions created by dissolving crystals (such as sugars and salts) in water Less osmotic pressure than colloids Can be expected to equilibrate more quickly between the vascular and extravascular spaces Two-thirds of infused crystalloid fluid leaves the vascular space within 1 hour 3 ml of a crystalloid solution is needed to replace 1 ml of blood Hypertonic solutions Have a higher osmotic pressure than that of body cells 5% dextrose in 0.9% sodium chloride 7.5% saline 5% dextrose in 0.45% sodium chloride Hypotonic solutions. Have a lower osmotic pressure than that of body cells Distilled water 0.45% sodium chloride (0.45% NaCl) 9

10 Isotonic Solutions. Colloids. Lactated Ringer's solution Normal saline Glucose-containing solutions (e.g., D5W) Solutions that contain molecules (usually protein) that are too large to pass through the capillary membrane Exhibit osmotic pressure and remain within the vascular compartment for a considerable length of time Examples Whole blood Plasma Packed red blood cells Theory of Fluid Flow. Key Principles in Managing Shock. The flow of fluid through a catheter is directly related to its diameter (to the fourth power) and inversely related to its length Other factors that affect fluid flow include: The diameter and length of the tubing The size of the vein The viscosity and temperature of the IV fluid Viscosity is affected by temperature Warm fluids generally flow better than cold ones Establish and maintain an open airway Administer high-concentration oxygen and assist ventilation as needed Control external bleeding (if present) Control external bleeding (if present) Initiate IV fluid replacement if appropriate Maintain patient's normal body temperature Monitor cardiac rhythm and oxygen saturation Frequently reassess vital signs 10

11 Hypovolemic Shock. Cardiogenic Shock. Treatment is not considered complete until the circulatory deficit and its causes are corrected Crystalloid fluid replacement for simple dehydration Volume replacement for hemorrhage Definitive surgery Critical care support Postoperative rehabilitation Treatment is directed toward improving the pumping action of the heart and managing cardiac rhythm irregularities Fluid replacement Drug therapy (varies by cause) Patients with cardiogenic shock secondary to myocardial ischemia or infarction require: Reperfusion strategies Possible circulatory support Tension pneumothorax and cardiac tamponade must be managed immediately Neurogenic Shock. Anaphylactic Shock. Treatment is similar to treatment for hypovolemia Care must be taken during IV therapy to avoid circulatory overload Closely monitor lung sounds for pulmonary congestion Use of vasopressors may be indicated Subcutaneous administration of epinephrine is treatment of choice in acute anaphylactic reactions Depending on severity, other therapy may include: Oral, IV, or IM administration of antihistamines Bronchodilators to treat bronchospasm Steroids to reduce the inflammatory response Crystalloid volume replacement Aggressive airway management should be anticipated 11

12 Septic Shock. Integration of Patient Assessment and the Treatment Plan. Treatment may include the management of hypovolemia (if present) and the correction of metabolic acid-base imbalance Prehospital care may include: Fluid resuscitation Respiratory support Vasopressors to improve cardiac output A thorough history (to help determine the source of the sepsis) The goals of care for the patient with severe hemorrhage or shock include: Rapid recognition of the event Initiation of treatment Prevention of additional injury Microcirculation in shock. Normal (1, 2), vasoconstriction (3), capillary opening (4), DIC (5), tissue death (6). Compensated shock. This stage of shock is reversible. 12

13 Uncompensated shock. This stage of shock is reversible. Irreversible shock. Death will ensue within 1 day to 3 weeks. 13